Knife-blade fuse



July 2 4, 1923 l,463v038 l E. H. ELLISON KNIFE BLADE FUSE Filed April 27, 1920 2 Sheets-Sheet l lid Patented July 24, 1923.

UNITED STATES EDWARD H. ELLISON, 0,? JAMESTOWN,

PATENT OFFICE.

NEW YORK, ASSIGNOB T0 MONARCH RE- FILLABLE FUSE (10., OF JAMESTOWN, NEW YORK, A CORPORATION OF NEW YORK.

KNIFE-BLADE FUSE.

Application filed April 27, 1920.

To all whom it may concern:

Be it knownfthat I, EDWARD H. Bunsen, a citizen of the United States, residing at Jamestown, in the county of (Jhautauqua, State of New York, have invented certain new and useful Improvements in Knife- Blade Fuses, of which the following is a description, reference being had to the accompanying drawing, and to the figures of reference marked thereon.

This invention relates to knife blade fuses, and more particularly to that type in which the knife blades are aligned and held in fined position in the ends of casill by bridge in fuses of the above character, the bridge pieces and casing ends have generally been provided with interlocking lugs and notches for preventing twisting of the bridge pieces relative to the casing while the fuse was being assembled. Such interlocking connection presented 'a ready means of escape for the gases between these bridge pieces and the ends of the casing. Furthermore these bridge pieces which have been provided with registering open ended slots for the passage of the knife blades thercthrough have never provided-a smooth outer unbroken surface coextensive with the areas of the casing about the knife biade whereby a felt washer could be uniformiy pressed against said surface provide a. gas-tight joint. Another objection this prior type of fuse has been due to the en' cessive number of detachable parts which have rendered the assembly the fuse laborious and slow.

One of the objects of the present invention is to overcome the first-mentioned defeet by providing a fuse of the above type having bridge pieces held in a predetermined position relative to the casing for aligning the knife blade terminals, Wherein the end of the casing is smooth and unbroken against which the bridge pieces engage so that an efiective gas-tight joint may be secured.

Still another object of this invention is to provide a fuse of the above character with bridge pieces held in a predetermined position relative to the casing and movable across the ends thereof into contact with Serial m. 376,931.

the knife blades to align and support the same.

Another object of the invention is to pro vide a fuse of the above type having bridge pieces held in a predetermined position relative to the casing and engaging against the smooth and unbroken ends thereof to effect a gas-tight joint, said bridge pieces extending compietely across the end of said casing into contact with said knife blades to support and align the same and to entirely close the casing about said knife blades.

Another object of this invention is to provide a means for supporting the knife blades at each end of the casing which will entirely close the end of the casing about said knife blade so that the felt washer covering this closing means can be pressed by the end caps uniformly thereagainst throughout their entire area thus presenting a gas-tight joint around the projecting knife blade.

A further object of the invention is to provide fuse of the above character in which thesebridge pieces are supported by and close each end of the casing and have edges abutting and forming an opening for the knife blade, the bridge pieces being adapted to support each knife blade at points adjacent the owing walls, there being a projection-on each knife blade adapt ed to support the bridge pieces centrslly of said casing so that the bridge pieces are rigidly maintained in a plane parallei to the end of the casing and present a smooth unbroken surface about the knife blade against which the felt washer is pressed by the end cap.

An additional object of this invention resides pivoting these bridge pieces to each end of the casing so that they may swing across into substantial contact with the knife blades and fit snugly therearound to form closure for the casing end.

A further object of this invention is to reduce the number of detachable parts of a fuse of this character by permanently attaching the bridge pieces to the casing, and by non-detachably mountingythe usual felt and metallic'washers in-the end caps Still another object of the invention is to provide at fuse end cap comprising an open ended ferrule havingr'metal and felt washers non-detachably carried thereby and apertured to permit the passage of the fuse v knife blade therethrough, said washers being movable relatively to said ferrule to permit the assemblage of the fuse.

Another feature of the inventionsresides in providing a construction whereby the fusible link connected to the inner ends of the knife blade terminals within the casing is provided with an amperage mark on its outer end which projects with the knife blade through the gas-tight end of the cats ing outside of the end cap where it may be plainly seen.

These and other objects will in part be obvious and will in part be hereinafter more fully disclosed. i

Referring more particularlyto the accompanying drawings:

Figure 1 is a side elevation of the fuse illustrating a portion thereof in. cross section;

Fig. 2 is a cross sectional view of the same taken at right angles thereto; 1

Fig. 3 is an end view of the fuse with the end capsremoved showing the knife blade in section fitting snugly between the bridge pieces;

Fig. 4 is a skeleton view f the knife blade terminals, the bridge pieces and the end ca ig. 5 is a perspective view of the fusible link itself;

Fig. 6 is a sectional view-showing a modification of the connections between the bridge pieces and knife bla des;

Fig. 7 is a sectional view at right angles thereto;

Fig. 8 is an end view with the end caps removedg.

Fig. 9 is a group View of the casing, bridge pieces, knife blades and endeap, and

Fig. 10 is a plan view of the casing with the bridge pieces in open position.

Referring more particularly to the accompanying drawings, the ini ention comprises the usual insulating casing 1, preferably threaded in'teriorly to receive therein metal end ferrules 2 projectingbeyond the end of the casing and enlarged'radially to provide a threaded surface 3 flush with the outer diameter of the casing. The metallic ends of this casing presentusmcoth unbroken surfaces.

in order to align the knife blades l and 5 extending into each end of the casing, there are provided a. plurality of bridge pieces 6 and 7 at each end thereof which are held in a predetermined relation to the casing, erably by pivoting each on of them directly toftheend of the casing. T ese pivotal connections may be loose and detachable from casing, but preferably 1 pi r de the rivets 3 and 9 whereby the bridge ieces are permanently pivoted to the casing ends. The form and outline of these bridge pieces may vary, one construction is shown clearly in Fig. 3 wherein they are provided with abutting edges, apertured or forming an aperture, snugly fitting about the knife blade passing therethrough. As will be seen, these bridge pieces swing into substantial contact with the sides of each blade to make a substantial fit therewith and close the end of the casing thereabout. As seen in Fig. 4 each knife blade where it contacts with the bridge pieces is undercut and narrowed to its inner end to provide shoulders or contact surfaces 10, 11, which directly engage the bridge pieces 6 and 7 near the annular end of the casing. By means of this construction, when the bridge pieces are swung into closed position about the knife blades, the same are aligned and held in fixed position relative to the casing.

In order to prevent these bridge pieces from sagging at the center especially when they are made of relatively thin metal, I provide each knife blade at the inner portion thereof with a laterally projecting metal. ledge or stud 12 which as shown, projects from each side thereof in a plane subv stantially transverse to the plane of the knife blade and this stud is suitably spaced from the plane of the shoulder on the knife blade so that when the bridge pieces are swung into closed position they will be en gage'dby the same. Thus the bridge pi aresupported annularly by the end walls of the casing and inturn support thelmife blades by means of the shoulders 10, 11 near tie casing walls and. t o lateral projections in the rigid knife blades sup'iort the inner portions of the bri pieces centrally of the casingv The bridge pieces hell in closed position by means of the end caps 13, H- which have internal threads engaging the threads 3 on the ends of e casing l. outer ends of these caps are open and provided with inwardly turned flanges for non-detachably ret mine: the slotted metal washer 17 and 1- slotted felt or buck-skin washer 18., carried within said caps. Preferably the buck-slain washer is permanently attached to the inner face-of the washer, as by gluing. By means of this construction, when he end caps l3 and are scre ed home on the e casing, the cute metal washer 1'? v the inner felt or buck-skin washer 3.8, uniforrnly against and throughout the enire he bridge pieces 6 7 making the depth of the The ends of the knife blades 4 and 5 pro jecting within the casing 1 are provided With the usual nut and bolt terminals 19 and 20 which are engaged by open ended slots 21 and 22 in the ends of the copper fusible link 23 so that the link may be detached without removing the nuts from the ends of the threaded bolt.

In order that the capacity of the fuse may be readily observable from without the casing, I preferably extend the end 24 of the fusible link 23 beyond the open ended slot 21 and provide the same with an amperage mark 25, such as 175*. This end 24 of the fuse is preferably made fiat to fit in a shallow similarly shaped recess 26 formed in the face of the knife blade 4:, which recess extends from the inner terminal 19 along the length of the blade past the shoulders 10, 11 to a point which projects outside of the end cap when the same is tightly secured on the end of the casing so that the end 24 of the copper link 23 with the amperage mark 25 thereon will also project beyond the end of the casing where it can be plainly seen. By recem 26 equal to the thickness of the copper link terminal 25, the faces of the link and knife blade are preserved substantially flush so that the projection of the knife blade and fusible link through the bridge pieces 6 and 7 and end cap 13 is snug and prevents the escape of the gases therethrough.

It will be observed from Fig. 5 that the end 2d of the link 23 beyond the open ended slot 21 is suitably apertured as at 27 to pass over one of the laterally projecting lugs 12 on the knife blade.

In lieu of providing the lmife blade with such a laterally projecting supporting lug 12, each knife blade may be suitably notched as shown in Fig. 7 to provide spaced shoulders 28 and 29 into which the bridge pieces 6 and 7 may swing for aligning and holding the knife blades in fixed position relative to the casing 1. In such event, the aperture 27 at the end 28 of'the fusible link as shown in Fig. 5 is of course omitted. While any type of fusible link may be used in connection. with my improved fuse, i prefer to use the link illustrated Fig. 5 which I will not describe in detail inasmuch as it forms the subject of a separate application. filed by me.

The various advantages of a constructed as above are apparent. For instance, the pivoted bridge pieces automatically align the blades when swung into closed position and will hold assembled and positioned in the The bridge pieces are held in place by its end caps which also ress the washers tightly against the ion ge pieces and hold the parts the assembled against the outward force 0 gases when the fuse is bridge pieces are made very thin and the metal liable to bend or flex when the cap is screwed home so as not to make a tight joint between the parts at the center of the blade, then the bridge pieces will be supported at the central portion of the casing by means of the laterally projecting studs on the knife blades, and these metal projections, if desired, may be set far enough out so as to engage the bridge pieces centrally before the edges of the bridge pieces are clamped tight against the casing. thus insuring a tight joint at the center, the ultimate purpose being to get the support for the bridge pieces which Will hold them absolutely horizontal so that the metal end washer will clamp the buck-skin or felt washer both at the edges and centrally throughout the entire surface of the bridge pieces about the knife blade. Of course, as explained before, if these bridge pieces are made suiliciently heavy, these projections are not needed, and in the latter-construction, the spaced shoulders at the edge of the knife blades will be used for holding them against endwise movement relative to the casing.

it will be obvious from the above that varione minor changes in the details of construction and the arrangement of the parts may be made without departing from the spirit of the invention as set forth in the appended claims.

Having thus described the invention, what I claim as new and desire to secure by letters Patent, is

fuse comprising an insulating casing having substantially smooth unbroken ends, fusible link therein, a projecting knife blade at each end thereof extending into and forming connections with the fusible link, means for closing the ends of said casing, bridge pieces for aligning said knife blades said bridge pieces engaging said smooth unbroken ends to secure efiective gas-tight joint, held in predetermined position relatively to said casing by means independent of said closing means.

2. A comprising an insulating casa fusible link therein, a projecting its blade at each end thereof extending to and forming connections with the fusilinlr, bridge pieces attached to the case and held in a predetermined position tive to the casing and movable across ends there into contact with said knife blades align and support the same.

A "fuse comprising an insulating casing having substantially smooth unbroken h a L. ends, a ttusible link therein. a projecting k re blade each end thereof extending into and forming connections with the fusible link. means for closing the ends of said casing, bridge pieces engaging said smooth ends to effect a gas-tight joint, said bridge &

ieces extending completely across the end oi said casing into contact with said knife blade to support and align the same and to close the casing about said knife blades and means independent of said closing means for holding the bridge pieces in predetermined position relatively to said casing.

i. A fuse comprising an insulating casing having smooth unbroken ends, a fusible link therein, a projecting knife blade at each end thereof ending into and forming connections with the fusible link, bridge pieces heln a predetermined position relative to the casing enga g said smooth ends to reflect a gas-tight j int, said bridge pieces extending completely across the end of said casing Contact with said knife blade to and align the same to close the casing about said niie blades, said knife es central projections for supi ing said bridge pieces centraily of said fuse an insulating easis link the sin, a knife end extending into and 1 the fusible link, means atned to the casing movable across e h end the easinginto substantial con- "de to a closed Washer covering cap engaging each essing said means uniformly througiio an insulating c" ii therein,'a projecting l.

reofi i i g tl'ie fusible link, casing lying in a single ed to form a single opening aid cas j through which th blade projects and snugly means forming a smooth outer suriaee, felt wasner entirely covering said surface, and an end enw 111g said casing clamping Wash. uniformly against said means,

fuse comprising an insulating casins", a fusible link therein, a projecting knife blad at end thereof extending connecting with tne fusible link, means attached casing; and adapted to anc. orin asingle opening in each end said casing lirongh which the knife blade projects and snugly fits, said means i a smooth outer surface, a felt was entirely covering said surface, e" engaging said casing and clamping"- tenor nn iormly against said means. in i comprising an insulating usiole link therein, a projecting e 3 each end thereof extending into nscting with fusible link, to each end of the casing and e a smooth enter surface which said knife blade projects, a felt Washer entirely covering said surface, and an end cap engaging said casing and clamping said washer uniformly against said means.

9. A. fuse comprising an insulating casing, a fusible link therein, a projecting knife blade at each end thereof extending into and connecting with the fusible link, means attached to the casing and adapted to swing across each end of the easing into contact with lrnife blade to close the end of said casing, a felt Washer covering said means, and an end cap engaging each end of said casing and pressing said Washer against said means uniformly throughout the entire area.

10. A comprising an insulating casing, a fusible link therein, a projecting knife blade at end thereof extending into connecting with the fusible linli', means pivoted to casing adapted to close the ends thereof about the knife blades, a covering said means, an end cap e; each end of said casing and said Washer said means ont entire in -e comprising insulating c n g, a Iusioie 1K ther ii, projecting the=.-eof extending into 1th the fusible lin bridge i ca 0 each end oi i g and ii the ln'nie blade the towing, a Washer eans, d an end cap on easing and "essing; ainst bridge j nrising; an insula'ing oasierein, a projeeting knife thereof extendi into- 7 clesin each and forming q re nttingand poor e Diane pass: tsetsecans nag said means th i. '2 ,i o. s we tionirg mom iein, a I 1 .1 n i v "v lane ELo me eor extend into and connecting with the trusible link,

bridgepieces s1 snorted by and completely closing each e n of the casing and having edge e, forrmg an open as; for r said hi. age pieces on i ltni e supportin contactat points s and centrally held firmly? in on, and end cap-s said easing i J? clamping said bridge pieces tlierebetween.

an insulating casirnii'e blade i into casing limit,

to swing across each end of the easing into contact with the knife blade to support the same in fixed position, and end caps engaging said casing for clamping said means therebetween.

15. A fuse comprising an insulating casing, a fusible link therein, a projecting knife blade at each end thereof extending into and connecting with the fusible link, means pivoted to each end of said casing for holding each knife blade in fixed relation, and end caps engaging said casing for clamping said means therebetween.

16. A fuse comprising an insulating casing, a fusible link therein, a projecting knife blade at each end thereof extending into and connecting with the fusible link, means pivoted to each end of said casing and forming at their meeting edges an aperture for fit ting and positioning the knife blade passing therethrough, and an end cap engaging each end of said casing and clamping said means therebetween.

17. A fuse comprising an insulating casing, a fusible link therein, a projectingknife blade at each end thereof extending into and forming connections with the fusible link, each knife blade being provided with centrally arranged projections, and outer shoulders arranged in spaced parallel planes; bridge pieces pivoted to each end of said casing and adapted to swing between the planes of said projections and shoulders and form interlocking engagementtherewith, and an end cap engaging each end of said casing, and clamping said bridge pieces therebetween.

18. A fuse comprising an insulating casing. a fusible link therein, a projecting knife blade extending into each end thereof and connecting with the fusible link, blade supporting bridge pieces connected to and closing each end of said casing. an end cap including metal and fel t'washers connected thereto means for preventing the detachment of said washers from said cap. passing over the end of each knife blade and engaging said casing to provide a substantially gas-tight packing for said casing end.

19. A fuse end cap .romprising an open ended ferrule. a metal washer carried therebv and apertured to permit the passage of a fuse knife blade therethrough, means for retaining said washer in said ferrule, said means permitting the movement of said washer relatively to said ferrule.

20. An end cap for a fuse comprising an open ended ferrule provided with an inwardly projecting flange and interior threads, a metal washer loosely confined between said flange and threads, said washer being movable relatively to said ferrule.

In testimony whereof, I afiix my signature.

EDWARD H. ELLISON. 

